diff --git a/soc/nxp/lpc/lpc55xxx/Kconfig.defconfig b/soc/nxp/lpc/lpc55xxx/Kconfig.defconfig
index 80f20ada986..569d6c0e4a7 100644
--- a/soc/nxp/lpc/lpc55xxx/Kconfig.defconfig
+++ b/soc/nxp/lpc/lpc55xxx/Kconfig.defconfig
@@ -38,6 +38,10 @@ config LPC55XXX_SRAM_CLOCKS
 config LPC55XXX_USB_RAM
 	default y
 
+# Set to the minimal size of data which can be written.
+config FLASH_FILL_BUFFER_SIZE
+	default 512
+
 if SOC_LPC55S06
 
 config LPC55XXX_USB_RAM
diff --git a/soc/nxp/mcx/mcxnx4x/Kconfig.defconfig b/soc/nxp/mcx/mcxnx4x/Kconfig.defconfig
index cf464656374..c108869cf6e 100644
--- a/soc/nxp/mcx/mcxnx4x/Kconfig.defconfig
+++ b/soc/nxp/mcx/mcxnx4x/Kconfig.defconfig
@@ -20,4 +20,8 @@ config SYS_CLOCK_HW_CYCLES_PER_SEC
 	default 16000 if MCUX_LPTMR_TIMER
 	default 150000000 if CORTEX_M_SYSTICK
 
+# Set to the minimal size of data which can be written.
+config FLASH_FILL_BUFFER_SIZE
+	default 128
+
 endif # SOC_SERIES_MCXNX4X